The absence of structural fidelity precludes construct validity: Rejoinderto Naglieri on what the cognitive assessment system does and does not measure

In this rejoinder, we show that Naglieri's (1999a) commentary thoroughly fa ils to refute the results of Kranzler and Keith's (1999) research on the fa ctor structure of the Cognitive Assessment System (CAS). We begin by review ing contemporary theory of construct validity with an emphasis on the role of factor analysis in "strong" validation programs. Next, we respond to the main theoretical and empirical issues raised by Naglieri (1999a) in his co mmentary regarding the results of our confirmatory factor analyses of the s tandardization data of the GAS. Finally, we critique the external evidence of validity he presented and emphasize the need for further research on the factor structure of the GAS. We also express concern with Naglieri's conti nued selective and misleading use of quotations. In sum, our research indic ates that the CAS lacks structural fidelity, a necessary but not sufficient condition for construct validity. An absence of structural fidelity indica tes that the scaled scores derived from the CAS do not correspond to the un derlying theory upon which the: test is based. The external evidence of val idity presented by Naglieri in his rejoinder is therefore meaningless. Scho ol psychologists and other practitioners are advised to interpret the CAS w ith caution, if at all.